The blue part was easy -- just wait until after the sun set, and leave the white balance on "daylight" and there you go.

The period immediately after the sunset (aka civil twilight) is the period where even though you are standing in the earth's shadow, the sky above you is still get direct sunlight. Since it was overcast, it was still fairly bright, since clouds have a high albedo. And since the clouds are water, and water scatters blue more than any other color, the light from the clouds is predominantly blue. Most people would correct for the color cast and render the scene in warmer tones, but I liked it better with the blue look; it made the scene look more night-like. (This is the real reason that people tend to look blue in films -- they hot light the set, then apply blue gels to simulate night, so that you can have a "night feel" but still see the actors.)

They are dolomite stacks?????

I believe that they are basalt. It was off of the Oregon coast, and I think that most of our hardest rock, which means the stuff that lasts, is basalt. I'm not certain about that, though.